In this work, the influence of different EDM parameters (pulse current, pulse voltage, pulse on-time , pulse off-time) in finishing stage on  the surface roughness (Ra)  as a result of application copper electrode to a workpiece( cold work steel  DIN1.2379)  has been investigated. Design of the experiment was chosen as full factorial. Statistical analysis has been done and artificial neural network has been used to choose proper machining parameters and to reach certain surface roughness. The experiment results indicated a good performance of proposed method in optimization of such a complex and non-linear problems. تفاصيل المقالة

Assistive device equipment can improve the performance of sit-to-stand (STS), standing, and walking of people with lower limb disability. The motorized assistive device is usually expensive and the use of another assistive device also makes an excessive force in the upper and lower extremity during (STS) transfer, which is not desirable for patients. In addition, only a few number of the non-motorized assistive devices that support all three phases; namely, sit-to-stand, standing, and walking are available. Consequently, improving and creating the new technology seems essential in this case. In this paper, the design procedure of saddle-assistive device is described in order to make use of the linear actuator in (STS) transfer and walk. Experimental results orientation of the shoulder during (STS) was recorded in the lab. Then, based on this analysis and simulation, saddle-assistive devices(S-AD) were designed and prototyped. Function prototype of the (S-AD) was done in the lab on a healthy person in (STS) and walking and then was compared with (STS) in normal mode. It is proposed due to the integration of the three phases in one device. Other advantages are force reduction on lower limbs, creating conditions of stability, and independence for patients with lower limb disability. تفاصيل المقالة

Ultrasonic Vibration assisted Single Point Incremental Forming (UVaSPIF) process is an attractive and adaptive method in which a sheet metal is gradually and locally formed by a vibrating hemispherical-head tool. The ultrasonic excitation of forming tool reduces the average of vertical component of forming force and spring-back rate of the formed sample. The spring-back phenomenon is one of the most important geometrical errors in SPIF process, which appear in the formed sample after the process execution. In the present article, a statistical analysis and optimization of effective factors on this phenomenon is performed in the UVaSPIF process based on DOE (Design of Experiments) principles. For this purpose, RSM (Response Surface Methodology) is selected as the experiment design technique. The controllable factors such as vertical step size, sheet thickness, tool diameter, wall inclination angle, and feed rate is specified as input variables of the process. The obtained results from ANOVA (Analysis of Variance) and regression analysis of experimental data, confirm the accuracy of mathematical model. Furthermore, it is shown that the linear, quadratic, and interactional terms of the variables are effective on the spring-back phenomenon. To optimize the spring-back phenomenon, the finest conditions of the experiment are determined using desirability method, and statistical optimization is subsequently verified by conducting the confirmation test. تفاصيل المقالة

Incremental forming is one of the forming methods that is considered because of no need to specific die, especially for rapid prototyping. In this study, the incremental forming process is carried out by using a rotating tool and assisted ultrasonic vibration. Purpose of this research is to investigate the effect of rotation speed and ultrasonic vibrations in the incremental forming process. According to the obtained results, mean and maximum values of forming force reduced by using a rotating tool and applying ultrasonic vibrations. The results of surface roughness tests demonstrated that by increasing rotational speed, the surface roughness improved 44% and applying ultrasonic vibrations with tool rotation can reduce surface roughness about 74%. Applying ultrasonic vibrations lead to increase micro-hardness up to 84%, but, by increasing rotational speed, surface hardness slightly reduces. Results of straight groove test determined ultrasonic vibrations with the rotating tool can increase stretching limit up to 41.79% due to the affect on the sheet plasticity behavior. تفاصيل المقالة

Ultrasonic vibration assisted single point incremental forming (UVaSPIF) is based on localized plastic deformation in a sheet metal blank. It consists to deform gradually and locally the sheet metal using vibrating hemispherical-head tool controlled by a CNC milling machine. The ultrasonic excitation of forming tool reduces the vertical component of forming force. In addition, application of ultrasonic vibration reduces the surface roughness of the specimen. Surface roughness is one of the quantitative and qualitative parameters, which is used to assess the quality of the final product. In the present paper, a statistical analysis and optimization of effective factors on this parameter is performed in the UVaSPIF. For this purpose, response surface methodology (RSM) is selected as the experiment design technique. The controllable factors such as vertical step size, sheet thickness, tool diameter, wall inclination angle, and feed rate is specified as input variables of the process. The obtained results from analysis of variance (ANOVA) and regression analysis of experimental data confirm the accuracy of mathematical model. Furthermore, it is shown that the linear, quadratic, and interactional terms of the variables are effective on the surface roughness parameter. To optimize the surface roughness parameter, the finest conditions of the experiment are determined using desirability method, and statistical optimization is subsequently verified by conducting the confirmation test. تفاصيل المقالة

در این تحقیق تأثیر پارامترهای مختلف ماشینکاری تخلیه الکتریکی از قبیل شدت جریان جرقه، ولتاژ جرقه، زمان روشنی پالس و زمان خاموشی پالس بر روی سرعت براده‌برداری با استفاده از الکترود مس بر روی قطعه‌کار (فولاد سردکار DIN1.2379) مورد بررسی قرار گرفته است. طراحی آزمایش به صورت فاکتوریل کامل در مرحله‌ی پرداخت ماشینکاری انتخاب شده و از تحلیل آماری بر روی داده‌های آزمایش در این تحقیق استفاده شده است. در نهایت به منظورانتخاب مناسب پارامترهای ماشینکاری تخلیه الکتریکی، یک مدل ریاضی برای دستیابی به سرعت براده برداری مطلوب، ارائه شد. تفاصيل المقالة

In this study, turning operation of Monel K500 copper-nickel super-alloy was evaluated. Ceramic cutting tools with two different cutting noses (conventional and wiper) were utilized. At first, the experimental tests were designed by using central composite design method. After implementation of the tests, the statistical models for output data (surface roughness, cutting force, and flank wear) have been developed. Furthermore, the effect of cutting parameters on output data was taken into account with help of analysis of variance. In third step, the optimal cutting condition was introduced for both cutting tools by using response surface method. In total, it was revealed that low depth of cut and feed rate coupled with high cutting speed is an optimal condition for turning of Monel super-alloy when ceramic tools are selected. In particular, the positive effect of wiper tool on output data was more when depth of cut has been lower than the length of wiper edge. تفاصيل المقالة